Lambda functions are invoked by actually passing captured parameters to the function. value is equal to 0 at the point where the lambda is defined (and value is captured). Since you are capturing by value, it doesn’t matter what you do to value after the capture. If you had captured value by reference, then you … Read more
In C++11, when you use non static data member initialization at the point of declaration like you do here: struct SS {int a = 0; int s = 2;}; you make the class a non-aggregate. This means you can no longer initialize an instance like this: SS s{1,2}; To make this initialization syntax work for … Read more
This is a range based for loop, it has the same basic behavior of: for(auto it = deviceList.begin(); it != deviceList.end(); ++it) { const auto& ioDev = *it; } The range based for loop has quickly become one of my favorite constructs, it’s terse and when you need to iterate an entire range, works as … Read more
The return type must be determined at compile-time. You might use std::common_type (since C++11): For arithmetic types not subject to promotion, the common type may be viewed as the type of the (possibly mixed-mode) arithmetic expression such as T0() + T1() + … + Tn(). template < typename T, typename X> typename std::common_type<T, X>::type Max_Number … Read more
List-initialization cannot be used as an argument to an operator in the general case. Per Paragraph 8.5.4/1 of the C++11 Standard: […] List-initialization can be used — as the initializer in a variable definition (8.5) — as the initializer in a new expression (5.3.4) — in a return statement (6.6.3) — as a for-range-initializer (6.5) … Read more
#define STRINGIFY2(X) #X #define STRINGIFY(X) STRINGIFY2(X) #define A 2 Then STRINGIFY(A) will give you “2”. You can concatenate it with other string literals by putting them side by side. “I have the number ” STRINGIFY(A) “.” gives you “I have the number 2.”.
The behavior is undefined. [meta.unary.prop] template <class T, class… Args> struct is_constructible; T and all types in the parameter pack Args shall be complete types, (possibly cv-qualified) void, or arrays of unknown bound. That’s a precondition of the meta-function. A contract that your code violates. libc++ is being generous by notifying you. Mind you, that … Read more
The clause “If a conversion function is a member function,” was added to the working draft in N2798 as part of the Concepts wording per N2773 Proposed Wording for Concepts. N2798 12.3.2/1 reads (I’ll use bold to show additions, and strikeout to show removals): 1 A member function of a class X having no parameters, … Read more
I did this largely just because of how the situation evolved. Prior to C++11, there was only: vector<T>::push_back(const T&); With the introduction of rvalue references I recommended the addition of the overload: vector<T>::push_back(T&&); instead of changing the original signature to: template <class U> vector<T>::push_back(U&&); Part of this decision was made because of some concerns about … Read more
The only mention of restrict in the C++11 FDIS is on §17.2 [library.c]: The descriptions of many library functions rely on the C standard library for the signatures and semantics of those functions. In all such cases, any use of the restrict qualifier shall be omitted. So restrict is not in C++11.